(a) Field of the Invention
The present invention relates to a system and a method for measurement of voice over Internet protocol (VoIP) quality of experience (QoE) and a compensation method, and more particularly, to a method of measuring VoIP QoE in real time and performing after-treatment such as compensation for low quality on the basis of the measurement quality.
(b) Description of the Related Art
In general, a method of measuring the quality of a VoIP service attaches the greatest importance to objectivity, and primarily adopts an objective measurement method of performing evaluation with a result measured by using a measuring instrument or an agent-type measuring module.
Further, the quality measurement method also adopts a method of measuring the quality of the VoIP service on the basis of only a test measurement method irrespective of an actual call. For example, the quality measurement method that measures call quality in a predetermined website adopts a method of measuring a packet loss ratio or delay by sending a test packet to a predetermined server and determining the quality by using the measured value. Therefore, various phenomena generated in the actual call cannot be reflected.
An objective method of measuring voice quality of the VoIP service can largely be classified into three types.
The first type is a perceptual evaluation speech quality (PESQ) algorithm. The PESQ algorithm is a method of measuring the quality by using an audio sample for measuring standard voice quality. This method cannot directly measure the voice quality with respect to an actually generated call, but it can accurately measure the quality with respect to a predetermined interval. Further, multiple repetitive quality measurements that can be compared with each other can be performed.
However, most equipment adopting the algorithm is very expensive. When a failure occurs in a voice call service or a voice call service network is constructed, the equipment is used to only measure voice quality in the network.
The second type is a single-ended method for objective speed quality assessment (SMFOSQA) algorithm. This algorithm can directly measure the quality of the actually generated call without using an audio sample for measuring the standard voice quality. On the contrary, since the algorithm does not measure the voice quality by using the audio sample for measuring the standard voice quality, the algorithm has a very large measurement value error.
Further, hardware performance of a very large capacity is required to use the algorithm. However, since the algorithm can directly measure the voice quality of the actually generated call, the algorithm can more flexibly deal with substantial voice subscriber quality measurement of a substantial voice subscriber.
The third type is an E-Model method. This method is used to calculate an R-factor value and only measures the value with respect to the VoIP service. The reason for this is that it is assumed that the E-Model is available with respect to only the VoIP service which is performed on an IP network. This method can be implemented in a relatively simple manner. Since this method is still less expensive than the PESQ method or the SMFOSQA, most VoIP providers measure and manage the quality by using this method.
However, since the quality is measured and managed by the test measurement method regardless of the actual call, various phenomena generated in the actual call cannot be reflected. Further, although this method is used to measure the quality of the actual call, most parameters must be set as basic values.
In addition, since the performance of a VoIP terminal has already reached a very high level, the values of the parameters need not be measured. The reason for this is that it is assumed that the voice quality is most damaged when a packet is lost or delayed on a network. However, in reality, the performance of the VoIP terminal has a large influence on an actual VoIP call service user.
Recently, even though a problem of a terminal or an environment around the terminal that deteriorates QoE cannot be managed by the VoIP providers, the VoIP providers also want to measure the quality and manage subscribers by considering environments of the subscribers due to various reasons such as competition of VoIP providers. The requirement can be achieved only by a subjective part of the VoIP service user, and cannot be solved by the known objective measurement methods.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.